Enhancing adsorption efficiencies of organic molecules through covalently bonded structures of magnetic carbon nanoparticles

Abstract

This study introduces a facile method for synthesizing covalently bonded magnetic carbon nanoparticles (MCNs) in which carboxylic acid-functionalized activated carbon nanospheres (ACN-COOH) are con- nected with amine-terminated iron oxide nanoparticles (NPs) (Fe3O4-NH2) via a carbodiimide crosslink- ing reaction. The adsorption characteristics of the developed magnetic nanoparticles (ACN-Fe3O4) were investigated using a standard cationic dye (methylene blue, MB). Two additional MCNs (multi-core and core@shell structures) were also prepared, and their adsorption performances were extensively com- pared. The developed ACN-Fe3O4 material thoroughly utilizes the strengths of activated carbon and Fe3O4 themselves, exhibiting large specific surface areas (708.4 m2/g) and strong magnetic properties (40.3 emu/g), resulting in high adsorption capacity (349.5 mg/g) and recycling efficiency (76 % of adsorp- tion performance after four cycles). In addition, a study of the mechanism reveals that pore-filling pro- cesses are dominant with minor contributions from electrostatic interactions, p–p interactions, and n– p interactions. The developed covalently bonded magnetic carbon nanoparticles (ACN-Fe3O4) can thus be considered as competent adsorbents with the potential to compensate for the drawbacks of contem- porary MCNs, such as, low adsorption capacity, and weak magnetic properties.